LTC6601IUF-1-PBF [Linear]
Low Noise, 0.5% Tolerance, 5MHz to 28MHz, Pin Confi gurable Filter/ADC Driver; 低噪声, 0.5 %的容差,为5MHz至28MHz ,引脚可配置的配过滤器/ ADC驱动器型号: | LTC6601IUF-1-PBF |
厂家: | Linear |
描述: | Low Noise, 0.5% Tolerance, 5MHz to 28MHz, Pin Confi gurable Filter/ADC Driver |
文件: | 总40页 (文件大小:483K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
LTC6601-1
Low Noise, 0.5% Tolerance,
5MHz to 28MHz, Pin Configurable
Filter/ADC Driver
FEATURES
DESCRIPTION
The LTC®6601-1 is a very easy-to-use fully differential
2nd order active RC filter and driver. On-chip resistors,
capacitors,andamplifierbandwidtharetrimmedtoprovide
consistent and repeatable filter characteristics.
n
Pin Configurable Gain and Filter Response
Up to 28MHz
n
Few External Components Required
n
Resistors Trimmed to 0.5% Typical
Capacitors Trimmed to 0.5% Typical
n
Thefiltercharacteristicsarepin-strapconfigurable. Cutoff
frequencies range from 5MHz to 28MHz. Gain is pin-strap
programmable between –17dB and +17dB.
n
Very Low Noise: 80dB S/N in 100MHz Bandwidth
n
Very Low Distortion (2V ):
P-P
1MHz: –100dBc 2nd, –123dBc 3rd
10MHz: –72dBc 2nd, –103dBc 3rd
Adjustable Output Common Mode Voltage
Rail-to-Rail Output Swing
A three-state BIAS pin is provided to adjust amplifier
power consumption. Select between high performance,
low power (50% power reduction), and standby modes
with the BIAS pin.
n
n
n
n
Power Configurability and Low Power Shutdown
Tiny 0.75mm 20-Lead (4mm × 4mm) QFN Package
The LTC6601-1 is available in a compact 4mm × 4mm
16-pin leadless QFN package.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents including 6271719.
APPLICATIONS
n
Differential Input A/D Converter Driver
n
Antialiasing/Reconstruction Filter
n
Single-Ended to Differential Conversion/Amplification
n
Low Voltage, Low Noise, Differential Signal
Processing
n
Common Mode Voltage Translation
TYPICAL APPLICATION
19MHz, 2nd Order Lowpass Filter. Gain = 6dB
Frequency Response
10
5
0
20
19
18
17
16
LTC6601-1
–
1
2
3
4
5
15
14
13
12
11
–5
+
3V
0.1μF
+
–10
–15
–20
–25
–30
V
OUT
V
3V
IN
–
–
+
0.1μF
6
7
8
9
10
1
10
100
FREQUENCY (MHz)
66011 TA01a
66011 TA01b
66011f
1
LTC6601-1
ABSOLUTE MAXIMUM RATINGS
PIN CONFIGURATION
(Note 1)
+
–
Total Supply Voltage (V to V )...............................5.5V
TOP VIEW
+
–
Input Voltage (Any Pin) (Note 2)..V + 0.3V to V –0.3V
Input Current (V , BIAS).................................. 10mA
20 19 18 17 16
OCM
Input Current (Pins 1, 5) (Note 2)........................ 20mA
Input Current (Pins 2, 4) (Note 2)........................ 30mA
Input Current (Pins 6, 20) (Note 2)...................... 15mA
Input Current (Pins 7, 8, 9, 10, 16, 17, 18, 19)
(Note 2)................................................................ 10mA
Output Short-Circuit Duration (Note 3) ............ Indefinite
Operating Temperature Range (Note 4)....–40°C to 85°C
Specified Temperature Range (Note 5) ....–40°C to 85°C
Junction Temperature ........................................... 150°C
Storage Temperature Range...................–65°C to 150°C
+
–
IN2
IN1
OUT
1
2
3
4
5
15
14
13
12
11
+
+
V
–
BIAS
V
21
8
–
IN1
V
OCM
+
–
IN2
OUT
6
7
9 10
UF PACKAGE
20-LEAD (4mm s 4mm) PLASTIC QFN
T
= 150°C, θ = 37°C/W, θ = 2°C/W
JA JC
JMAX
–
EXPOSED PAD (PIN 21) IS V , MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC6601CUF-1#PBF
LTC6601IUF-1#PBF
LTC6601CUF-1#TRPBF
LTC6601IUF-1#TRPBF
66011
66011
0°C to 70°C
–40°C to 85°C
20-Lead (4mm × 4mm) Plastic QFN
20-Lead (4mm × 4mm) Plastic QFN
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
DC ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. V+ = 3V, V– = 0V, VINCM = VOCM = mid-supply, BIAS tied to V+ or floating,
ILOAD = 0, RBAL = 100k. The filter is configured for a gain of 1 unless otherwise noted. VS is defined as (V+ – V–). VOUTCM is defined as
(VOUT+ + VOUT–)/2. VINCM is defined as (VINP + VINM)/2. VOUTDIFF is defined as (VOUT+ – VOUT–). VINDIFF is defined as (VINP – VINM). See
Figure 1.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
+
l
l
V
(Note 6)
Amplifier Differential Offset Voltage (Input
Referred)
V = 2.7V to 5.25V, BIAS = V
0.25
0.25
1
1.5
mV
mV
OSDIFF
S
BIAS = Floating
Ampifier Differential Offset Voltage Drift
(Input Referred)
V = 2.7V to 5.25V
S
1
μV/°C
ΔV
/ΔT
OSDIFF
(Note 6)
+
R
IN
(Note 14)
Input Resistance, BIAS = V
Single Ended Input Resistance, Pin 2 or Pin 4 V = 3V
Differential Input Resistance
133
200
Ω
Ω
S
V = 3V
S
66011f
2
LTC6601-1
DC ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. V+ = 3V, V– = 0V, VINCM = VOCM = mid-supply, BIAS tied to V+ or floating,
ILOAD = 0, RBAL = 100k. The filter is configured for a gain of 1 unless otherwise noted. VS is defined as (V+ – V–). VOUTCM is defined as
(VOUT+ + VOUT–)/2. VINCM is defined as (VINP + VINM)/2. VOUTDIFF is defined as (VOUT+ – VOUT–). VINDIFF is defined as (VINP – VINM). See
Figure 1.
SYMBOL
ΔR (Note 14)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
+
Input Resistance Match, BIAS = V
Single Ended Input Resistance, Pin 2 or Pin 4 V = 3V
IN
l
0.25
Ω
S
+
l
l
I (Note 7)
B
Internal Amplifier Input Bias
V = 2.7V to 5V
S
BIAS = V
–50
–25
–25
–12.5
0
0
μA
μA
BIAS = Floating
+
l
l
I
(Note 7)
Internal Amplifier Input Offset
V = 2.7V to 5V
S
BIAS = V
1
1
10
5
μA
μA
OS
BIAS = Floating
V
INCM
(Note 8)
Input Signal Common Mode Range
(V + V )/2
INP
INM
+
l
l
BIAS = V , V
= 1.5V
= 2.5V
V = 3V
0
0
1.7
4.7
V
V
OCM
OCM
S
+
BIAS = V , V
V = 5V
S
l
l
BIAS Pin Floating, V
BIAS Pin Floating, V
= 1.5V
= 2.5V
V = 3V
S
0
0
1.8
4.8
V
V
OCM
OCM
S
V = 5V
CMRRI
(Notes 9, 14)
Input Common Mode Rejection Ratio
(Amplifier Input Referred) ΔV /ΔV
INCM
INCM
OSDIFF
ΔV
= 2.5V
V = 5V
74
70
dB
dB
S
CMRRO
(Notes 9, 14)
Output Common Mode Rejection Ratio
(Amplifier Input Referred) ΔV /ΔV
OCM
OCM
OSDIFF
ΔV
= 1V
V = 5V
S
PSRR (Note 10)
Power Supply Rejection Ratio
(Amplifier Input Referred) ΔV /ΔV
S
OSDIFF
+
l
l
BIAS = V
V = 2.7V to 5V
66
60
95
95
dB
dB
S
BIAS Pin Floating
V = 2.7V to 5V
S
PSRRCM (Note 10) Common Mode Power Supply Rejection Ratio
(ΔV /ΔV
l
)
V = 2.7V to 5V
46
60
1
dB
V/V
%
S
OSCM
S
g
Common Mode Gain (ΔV
OCM
/ΔV
OUTCM
)
OCM
cm
V = 5V
S
ΔV
= 2V
Common Mode Gain Error = 100 • (g – 1)
cm
l
ΔV
= 2V
V = 5V
S
0.1
0.3
OCM
BAL
Output Balance (ΔV
Single-Ended Input
Differential Input
/ΔV
OUTCM
)
ΔV
S
V = 5V
S
= 2V
OUTDIFF
OUTDIFF
l
l
–62
–63
–40
–40
dB
dB
V = 5V
+
l
l
V
Common Mode Offset Voltage
(V – V
V = 2.7V to 5V
S
BIAS = V
5
8
15
20
mV
mV
OSCM
S
)
V = 2.7V to 5V
BIAS = Floating
OUTCM
OCM
+
l
l
Common Mode Offset Voltage Drift
(V – V
V = 2.7V to 5V
S
BIAS = V
5
20
μV/°C
μV/°C
ΔV
/ΔT
OSCM
S
)
V = 2.7V to 5V
BIAS = Floating
OUTCM
OCM
V
(Note 8) Output Signal Common Mode Range
OUTCMR
+
+
l
l
l
l
(Voltage Range for the V
Pin)
V = 3V
BIAS = V
1.1
1.1
1.1
1.1
1.7
4
1.8
4
V
V
V
V
OCM
S
V = 5V
BIAS = V
S
V = 3V
BIAS Pin Floating
BIAS Pin Floating
S
V = 5V
S
l
l
R
Input Resistance, V
Pin
V = 3V
12.5
18
23.5
kꢀ
V
INVOCM
OCM
S
V
MID
Voltage at the V
PIn
V = 3V
S
1.475
1.5
1.525
OCM
66011f
3
LTC6601-1
DC ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. V+ = 3V, V– = 0V, VINCM = VOCM = mid-supply, BIAS tied to V+ or floating,
ILOAD = 0, RBAL = 100k. The filter is configured for a gain of 1 unless otherwise noted. VS is defined as (V+ – V–). VOUTCM is defined as
(VOUT+ + VOUT–)/2. VINCM is defined as (VINP + VINM)/2. VOUTDIFF is defined as (VOUT+ – VOUT–). VINDIFF is defined as (VINP – VINM). See
Figure 1.
SYMBOL
PARAMETER
CONDITIONS
V = 3V, I = 0mA
MIN
TYP
MAX
UNITS
+
+
+
+
+
+
l
l
l
l
l
l
V
Output Voltage, High, Either Output Pin
(Note 11)
BIAS = V
V = 3V, I = –5mA BIAS = V
245
285
415
350
390
550
450
525
750
625
700
1000
mV
mV
mV
mV
mV
mV
OUT
S
L
S
L
V = 3V, I = –20mA BIAS = V
S
L
V = 5V, I = 0mA
BIAS = V
V = 5V, I = –5mA BIAS = V
S
L
S
L
V = 5V, I = –20mA BIAS = V
S
L
l
l
l
l
l
l
V = 3V, I = 0mA, BIAS Pin Floating
240
290
470
370
430
650
450
525
850
675
775
1100
mV
mV
mV
mV
mV
mV
S
L
V = 3V, I = –5mA, BIAS Pin Floating
S
L
V = 3V, I = –20mA, BIAS Pin Floating
S
L
V = 5V, I = 0mA, BIAS Pin Floating
S
L
V = 5V, I = –5mA, BIAS Pin Floating
S
L
V = 5V, I = –20mA, BIAS Pin Floating
S
L
+
+
+
+
+
+
l
l
l
l
l
l
Output Voltage, Low, Either Output Pin
(Note 11)
V = 3V, I = 0mA
BIAS = V
BIAS = V
120
135
195
175
200
270
225
250
350
325
360
475
mV
mV
mV
mV
mV
mV
S
L
V = 3V, I = 5mA
S
L
V = 3V, I = 20mA BIAS = V
S
L
V = 5V, I = 0mA
BIAS = V
BIAS = V
S
L
V = 5V, I = 5mA
S
L
V = 5V, I = 20mA BIAS = V
S
L
l
l
l
l
l
l
V = 3V, I = 0mA, BIAS Pin Floating
110
120
170
150
170
225
200
225
300
270
300
400
mV
mV
mV
mV
mV
mV
S
L
V = 3V, I = 5mA, BIAS Pin Floating
S
L
V = 3V, I = 20mA, BIAS Pin Floating
S
L
V = 5V, I = 0mA, BIAS Pin Floating
S
L
V = 5V, I = 5mA, BIAS Pin Floating
S
L
V = 5V, I = 20mA, BIAS Pin Floating
S
L
l
l
I
Output Short-Circuit Current,
Either Output Pin (Note 12)
V = 3V
S
45
60
65
90
mA
mA
SC
S
V = 5V
l
V
S
Supply Voltage Range
2.7
5.25
V
+
l
l
l
I
Supply Current, BIAS Pin Tied to V
V = 2.7V
32.9
33.1
33.9
43
43.5
45
mA
mA
mA
S
S
V = 3V
S
V = 5V
S
l
l
l
Supply Current, BIAS Pin Floating
V = 2.7V
16.0
16.2
16.9
25
mA
mA
mA
S
V = 3V
25.5
26.5
S
V = 5V
S
–
l
l
l
I
Supply Current, BIAS Pin Tied to V
V = 2.7V
0.34
0.35
0.55
0.9
1
1.6
mA
mA
mA
SHDN
S
V = 3V
S
V = 5V
S
–
–
l
l
l
l
l
V
V
V
BIAS Input Pin Range for Shutdown
(Note 13) BIAS Input for Half Power Operation
BIAS Input for High Performance Operation
BIAS Input Resistance
V = 2.7V to 5V
S
V
V + 0.4
V
V
BIASSD
BIASLP
BIASHP
–
–
V = 2.7V to 5V
S
V + 1.0
V + 1.5
–
+
V = 2.7V to 5V
S
V + 2.3
V
V
R
V = 2.7V to 5V
S
100
150
200
kꢀ
V
BIAS
BIAS
–
–
–
V
BIAS Float Voltage
V = 2.7V to 5V
S
V + 1.05 V + 1.12 V + 1.25
t
Turn-On Time
V = 3V, V
= 0.25V to 3V
= 3V to 0.25V
400
400
ns
ns
ON
OFF
S
SHDN
SHDN
t
Turn-Off Time
V = 3V, V
S
66011f
4
LTC6601-1
AC ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. V+ = 3V, V– = 0V, VINCM = VOCM = mid-supply, VBIAS is tied to V+ or
+
floating, unless otherwise noted. (See Figure 2 for the AC test configuration.) VS is defined as (V+ – V–). VOUTCM is defined as (VOUT
+
VOUT–)/2. VICM is defined as (VINP + VINM)/2. VOUTDIFF is defined as (VOUT+ – VOUT–). VINDIFF is defined as (VINP – VINM).
SYMBOL
PARAMETER
CONDITIONS
ΔV = 0.25V, f
MIN
TYP
MAX
UNITS
l
l
l
l
l
l
l
l
GAIN
Filter Gain, See Figure 2,
–0.25
0.05
0
0.02
0.11
–0.34
–2.35
–6.24
0.25
dB
dB
dB
dB
dB
dB
dB
dB
= DC (Note 14)
TEST
IN
+
BIAS Pin Tied to V ,
V
V
V
V
V
V
V
= 600mV , f
= 1MHz
IN
IN
IN
IN
IN
IN
IN
P-P TEST
P-P TEST
AC Gain Measurements Relative to 1MHz
–0.08
–0.01
–0.54
–2.75
–7.14
0.12
0.23
–0.14
–1.95
–5.34
= 600mV , f
= 2MHz
= 5MHz
= 10MHz
= 14.45MHz
= 20MHz
= 50MHz
= 600mV , f
P-P TEST
= 600mV , f
P-P TEST
= 600mV , f
P-P TEST
= 600mV , f
P-P TEST
–23.70 –21.70 –19.70
= 600mV , f
P-P TEST
l
l
l
l
l
l
l
l
PHASE
Filter Phase, See Figure 2,
0
Deg
Deg
Deg
Deg
Deg
Deg
Deg
Deg
ΔV = 0.25V, f
= DC
IN
TEST
+
BIAS Pin Tied to V
–6.0
–12.0
–30.7
–67.6
–100.1
–5.4
–10.8
–28.2
–62.6
–94.1
–4.8
–9.6
–25.7
–57.6
–88.1
V
V
V
V
V
V
V
= 600mV , f
= 1MHz
IN
IN
IN
IN
IN
IN
IN
P-P TEST
P-P TEST
= 600mV , f
= 2MHz
= 5MHz
= 10MHz
= 14.45MHz
= 20MHz
= 50MHz
= 600mV , f
P-P TEST
= 600mV , f
P-P TEST
= 600mV , f
P-P TEST
–127.3 –122.3 –117.3
–169.3
= 600mV , f
P-P TEST
= 600mV , f
P-P TEST
NOISE
SNR
Wide Band Output Noise, 14.45MHz Cutoff,
BW = 100MHz
BW = 20MHz
71
54
μV
μV
RMS
RMS
+
BIAS Pin Tied to V
+
BIAS Pin Tied to V
BW = 100MHz
BW = 20MHz
80
82.3
dB
dB
+
DISTORTION V = 2V , 10MHz, BIAS Pin Tied to V
HD2, Single-Ended Input
HD3, Single-Ended Input
HD2, Differential Input
HD3, Differential Input
–70
–103
–72
dBc
dBc
dBc
dBc
IN
P-P
–103
f TC
O
Cutoff Frequency Temperature Coefficient
–120
ppm/°C
l
l
l
l
l
l
l
l
GAIN
Filter Gain, See Figure 2,
BIAS Pin Floating (Remaining AC
Measurements Relative to 1MHz)
–0.25
0.05
0
0.02
0.11
–0.34
–2.50
–6.53
0.25
dB
dB
dB
dB
dB
dB
dB
dB
ΔV = 0.25V, f
= DC (Note 14)
IN
TEST
V
V
V
V
V
V
V
= 600mV , f
= 1MHz
IN
IN
IN
IN
IN
IN
IN
P-P TEST
P-P TEST
–0.08
–0.01
–0.54
–2.90
–7.43
0.12
0.23
–0.14
–2.10
–5.63
= 600mV , f
= 2MHz
= 5MHz
= 10MHz
= 14.45MHz
= 20MHz
= 50MHz
= 600mV , f
P-P TEST
= 600mV , f
P-P TEST
= 600mV , f
P-P TEST
= 600mV , f
P-P TEST
–23.90 –21.90 –19.90
= 600mV , f
P-P TEST
l
l
l
l
l
l
l
l
PHASE
Filter Phase, See Figure 2,
BIAS Pin Floating
0
Deg
Deg
Deg
Deg
Deg
Deg
Deg
Deg
ΔV = 0.25V, f
= DC
IN
TEST
–6.0
–12.4
–31.8
–70.2
–103.5
–5.5
–11.2
–29.3
–65.2
–97.5
–4.8
–10.0
–26.8
–60.2
–91.5
V
V
V
V
V
V
V
= 600mV , f
= 1MHz
IN
IN
IN
IN
IN
IN
IN
P-P TEST
P-P TEST
= 600mV , f
= 2MHz
= 5MHz
= 10MHz
= 14.45MHz
= 20MHz
= 50MHz
= 600mV , f
P-P TEST
= 600mV , f
P-P TEST
= 600mV , f
P-P TEST
–130.1 –125.1 –120.1
–173.6
= 600mV , f
P-P TEST
= 600mV , f
P-P TEST
NOISE
SNR
Output Noise, See Figure 2,
BIAS Pin Floating
BW = 100MHz
BW = 20MHz
78
58
μV
μV
RMS
RMS
BIAS Pin Floating
BW = 100MHz
BW = 20MHz
79
81.7
dB
dB
Distortion
V
IN
= 2V , 10MHz, BIAS Pin Floating
HD2, Single-Ended Input
HD3, Single-Ended Input
HD2, Differential Input
HD3, Differential Input
–64
–71
–70
–72
dBc
dBc
dBc
dBc
P-P
f TC
O
Cutoff Frequency Temperature Coefficient
–120
ppm/°C
66011f
5
LTC6601-1
ELECTRICAL CHARACTERISTICS
Note 1: Stresses beyond those listed under the Absolute Maximum
Ratings may cause permanent damage to the device. Exposure to any
Absolute Maximum Rating condition for extended periods may affect
device reliability and lifetime.
the mid-supply common mode input case by more than 1%, and the
common mode offset (V ) has not deviated from the mid-supply
common mode offset by more than 10mV.
OCMOS
The voltage range for the output common mode range is tested using the
test circuit of Figure 1 by measuring the differential DC gain with V
=
Note 2: All pins are protected by steering diodes to either supply. If any
pin is driven beyond the part’s supply voltage, the excess input current
(current in excess of what it takes to drive that pin to the supply rail)
should be limited to less than 10mA.
OCM
mid-supply, and again with a voltage set on the V
pin at the Electrical
OCM
Characteristics table limits, checking the differential gain has not deviated
from the mid-supply common mode input case by more than 1%, and that
the common mode offset (V
from the mid-supply case.
Note 9: Input CMRR is defined as the ratio of the change in the input
common mode voltage at the amplifier input to the change in differential
input referred voltage offset. Output CMRR is defined as the ratio of the
change in the voltage at the V
referred voltage offset.
Note 10: Power supply rejection (PSRR) is defined as the ratio of the
change in supply voltage to the change in differential input referred voltage
offset. Common mode power supply rejection (PSRRCM) is defined as the
ratio of the change in supply voltage to the change in the common mode
) has not deviated by more than 10mV
OCMOS
Note 3: A heat sink may be required to keep the junction temperature
below the Absolute Maximum Rating when the output is shorted
indefinitely. Long-term application of output currents in excess of the
Absolute Maximum Ratings may impair the life of the device.
Note 4: The LTC6601C/LTC6601I are guaranteed functional over the
operating temperature range –40°C to 85°C.
Note 5: The LTC6601C is guaranteed to meet specified performance from
0°C to 70°C. The LTC6601C is designed, characterized, and expected
to meet specified performance from –40°C to 85°C but is not tested or
QA sampled at these temperatures. The LTC6601I is guaranteed to meet
specified performance from –40°C to 85°C.
Note 6: Output referred voltage offset is a function of the low frequency
gain of the LTC6601. To determine output referred voltage offset, or output
voltage offset drift, multiply this specification by the noise gain (1 + GAIN).
See Applications Information for more details.
pin to the change in differential input
OCM
offset, V
/V
.
OUTCM OCM
Note 11: Output swings are measured as differences between the output
and the respective power supply rail.
Note 12: Extended operation with the output shorted may cause junction
temperatures to exceed the 150°C limit and is not recommended.
Note 7: Input bias current is defined as the average of the currents
flowing into the noninverting and inverting inputs of the internal amplifier
and is calculated from measurements made at the pins of the IC. Input
offset current is defined as the difference of the currents flowing into the
noninverting and inverting inputs of the internal amplifier and is calculated
from measurements made at the pins of the IC.
Note 13: Floating the BIAS pin will reliably place the part into the half-
power mode. The pin does not have to be driven. Care should be taken,
however, to prevent external leakage currents in or out of this pin from
pulling the pin into an undesired state.
Note 14: The variable contact resistance of the high speed test equipment
limits the accuracy of this test. These parameters only show a typical
value, or conservative minimum and maximum value.
Note 8: Input common mode range is tested using the test circuit of
Figure 1 by measuring the differential DC gain with V
= mid-supply, and
ICM
with V
at the input common mode range limits listed in the Electrical
ICM
Characteristics table, verifying the differential gain has not deviated from
66011f
6
LTC6601-1
TYPICAL PERFORMANCE CHARACTERISTICS
High Performance Supply Current
vs Temperature and
Shutdown Supply Current
vs Temperature and
Supply Voltage
Low Power Supply Current
vs Temperature and
Supply Voltage
Supply Voltage
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
18.0
17.5
17.0
16.5
16.0
15.5
15.0
35
34
33
32
31
30
V
= V
= MID-SUPPLY
OCM
V
= V
= MID-SUPPLY
V
= V
= MID-SUPPLY
OCM
INCM
INCM
OCM
INCM
–
+
BIAS PIN TIED TO V
BIAS PIN FLOATING
BIAS PIN TIED TO V
5V
5V
3V
5V
2.7V
3V
3V
2.7V
2.7V
–50 –25
0
25
50
75 100 125
–50 –25
0
25
50
75 100 125
–50 –25
0
25
50
75 100 125
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
66011 G03
66011 G01
66011 G02
Shutdown Supply Current
vs Supply Voltage and Temperature
Supply Current vs Bias Pin
Voltage and Temperature
Low Power Mode Supply Current
vs Supply Voltage and Temperature
50
40
30
20
10
0
1
0.1
100
10
V
V
= V
= MID-SUPPLY
OCM
INCM
S
= 3V
125°C
125°C
–40°C
25°C
1
–40°C
25°C
0.1
0.01
0.001
–40°C
25°C
125°C
0.01
0.001
V
= V
= MID-SUPPLY
OCM
V
= V
= MID-SUPPLY
OCM
INCM
INCM
–
BIAS PIN TIED TO V
BIAS PIN FLOATING
0
0.5
1
1.5
2
2.5
3
0
1
2
3
4
5
0
1
2
3
4
5
–
BIAS PIN VOLTAGE WITH RESPECT TO V (V)
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
66011 G04
66011 G05
66011 G06
High Performance Supply Current
vs Supply Voltage and Temperature
High Performance Mode
Differential VOS vs Temperature
Low Power Mode Differential VOS
vs Temperature
100
10
1.00
0.75
1.00
0.75
V
V
= 3V
INCM
BIAS PIN TIED TO V
V
V
= 3V
S
INCM
BIAS PIN FLOATING
S
= V
= MID-SUPPLY
= V
= MID-SUPPLY
OCM
OCM
125°C
+
5 REPRESENTATIVE UNITS
5 REPRESENTATIVE UNITS
0.50
0.50
–40°C
0.25
0.25
1
0.00
0.00
0.1
–0.25
–0.50
–0.75
–1.00
–0.25
–0.50
–0.75
–1.00
25°C
0.01
0.001
V
= V
= MID-SUPPLY
OCM
INCM
+
BIAS PIN TIED TO V
0
1
2
3
4
5
–50 –25
0
25
50
75 100 125
–50 –25
0
25
50
75 100 125
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
TEMPERATURE (°C)
66011 G07
66011 G08
66011 G09
66011f
7
LTC6601-1
TYPICAL PERFORMANCE CHARACTERISTICS
High Performance Common Mode
VOS vs Temperature
Low Power Common Mode VOS
vs Temperature
Internal Amplifier Input Bias
Current vs Temperature
15
10
5
–5
–10
–15
–20
–25
–30
10
5
LOW POWER MODE
(BIAS PIN FLOATING)
0
0
HIGH PERFORMANCE MODE
+
(BIAS PIN TIED TO V )
–5
–10
–15
–5
V
V
= 3V
INCM
BIAS PIN FLOATING
V
V
= 3V
INCM
BIAS PIN TIED TO V
S
S
= V
= MID-SUPPLY
OCM
= V
= MID-SUPPLY
OCM
+
V
V
= 3V
S
INCM
= V
= MID-SUPPLY
5 REPRESENTATIVE UNITS
OCM
0
5 REPRESENTATIVE UNITS
–10
–50 –25
0
25
50
75 100 125
–50 –25
25
50
75 100 125
–50 –25
0
25
50
75 100 125
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
66011 G11
66011 G12
66011 G10
BIAS Pin Float Voltage
vs Temperature
Filter Input Resistance
vs Temperature
BIAS Pin Input Resistance
vs Temperature
1.20
1.15
1.10
1.05
1.00
1.0050
1.0025
1.0000
0.9975
0.9950
200
175
150
125
100
V
V
= 3V
S
INCM
NOMINAL
NOMINAL
V
V
= 3V
INCM
V
V
= 3V
INCM
S
S
= V = MID-SUPPLY
= V
= MID-SUPPLY
OCM
= V
= MID-SUPPLY
OCM
OCM
R
R
= 200Ω DIFFERENTIAL
= 133.3Ω SINGLE-ENDED
SEE FIGURE 1 FOR CONFIGURATION
SINGLE-ENDED
DIFFERENTIAL
–50 –25
0
25
50
75 100 125
–50 –25
0
25
50
75 100 125
–50 –25
0
25
50
75 100 125
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
66011 G14
66011 G15
66011 G13
High Performance Mode
Frequency Response of 12
Possible Filter Configurations
Low Power Mode Frequency
Response of 12 Possible Filter
Configurations
Low Frequency Gain
vs Temperature
1.010
1.005
1.000
0.995
0.990
V
V
= 3V
INCM
S
= V
= MID-SUPPLY
OCM
10
0
10
0
5 REPRESENTATIVE UNITS
–10
–20
–30
–10
–20
–30
V
V
= 3V
INCM
BIAS PIN TIED TO V
V
V
= 3V
S
INCM
BIAS PIN FLOATING
S
= V
= MID-SUPPLY
= V
= MID-SUPPLY
OCM
OCM
+
–50 –25
0
25
50
75 100 125
0.1
1
10
100
0.1
1
10
100
TEMPERATURE (°C)
FREQUENCY (MHz)
FREQUENCY (MHz)
66011 G16
66011 G17
66011 G18
66011f
8
LTC6601-1
TYPICAL PERFORMANCE CHARACTERISTICS
High Performance Mode Gain
and Phase Repeatability of 10
Random Units
Low Power Mode Gain and Phase
Repeatability of 10 Random Units
0.20
0.15
0.10
0.05
0
4
0.20
0.15
0.10
0.05
0
4
V
V
= 3V
INCM
V
V
= 3V
S
INCM
S
= V
= MID-SUPPLY
= V
= MID-SUPPLY
OCM
OCM
3
3
+
BIAS PIN TIED TO V
SEE FIGURE 2
BIAS PIN FLOATING
SEE FIGURE 1
2
2
ϕ
– ϕ
AVERAGE
ϕ
MAX
– ϕ
AVERAGE
MAX
MAX – AVERAGE
1
1
MAX – AVERAGE
0
0
–0.05
–0.10
–0.15
–0.20
–1
–2
–3
–4
–0.05
–0.10
–0.15
–0.20
–1
–2
–3
MIN – AVERAGE
MIN – AVERAGE
ϕ
MIN
– ϕ
AVERAGE
ϕ
MIN
– ϕ
AVERAGE
–4
0.1
1
10
100
0.1
1
10
100
FREQUENCY (MHz)
FREQUENCY (MHz)
66011 G19
66011 G20
Low Power Mode Gain Error of
10 Random Units Normalized to
1MHz
High Performance Mode Gain Error
of 10 Random Units Normalized to
1MHz
High Performance Mode Phase
Error of 10 Random Units
3
2
15
10
5
3
2
V
V
= 3V
ICM
BIAS PIN FLOATING
V
V
= 3V
ICM
BIAS PIN TIED TO V+
V
V
= 3V
ICM
BIAS PIN TIED TO V+
S
S
S
= V
= MID-SUPPLY
OCM
= V
= MID-SUPPLY
OCM
= V
= MID-SUPPLY
OCM
10 RANDOM UNITS PLOTTED
T
10 RANDOM UNITS PLOTTED
T
10 RANDOM UNITS PLOTTED
T
= 25°C
= 25°C
= 25°C
A
A
A
1
1
+SPECIFICATION
+SPECIFICATION
+SPECIFICATION
0
0
0
–SPECIFICATION
–1
–2
–3
–5
–10
–15
–1
–2
–3
–SPECIFICATION
–SPECIFICATION
1
10
FREQUENCY (MHz)
100
1
10
FREQUENCY (MHz)
100
1
10
100
FREQUENCY (MHz)
66011 G22
66011 G23
66011 G21
Low Power Mode Phase Error of
10 Random Units
Turn On and Turn Off Transient
Response
Pulse Response
15
10
5
5
4
1.6
2
1
V
V
= 3V
ICM
BIAS PIN FLOATING
V
= 5V
V
= 3V
S
S
S
BIAS PIN
= V
= MID-SUPPLY
OCM
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
3
10 RANDOM UNITS PLOTTED
T
= 25°C
A
2
1
+SPECIFICATION
0
0
0
–1
–2
–3
–4
–5
–5
–10
–15
–SPECIFICATION
–1
–2
V
OUTDIFF
1
1
10
100
0
2
3
4
5
6
0
1
2
3
4
5
6
7
8
FREQUENCY (MHz)
TIME (μs)
TIME (μs)
66011 G24
66011 G25
66011 G26
66011f
9
LTC6601-1
TYPICAL PERFORMANCE CHARACTERISTICS
Distortion vs Frequency
Differential Output Noise
Distortion vs Frequency
–60
–70
100
10
1
100
10
1
–60
–70
V
V
V
= 5V
V
= 3V
V
V
V
= 5V
S
S
S
= 2V INPUT
FIGURE 2
= 2V INPUT
P-P
IN
P-P
IN
ICM
= V
= MID-SUPPLY
OCM
= V
ICM
OCM
INTEGRATED NOISE,
BIAS PIN FLOATING
BIAS PIN TIED TO V+
FIGURE 2
= MID-SUPPLY
–80
BIAS PIN FLOATING
FIGURE 2
–80
INTEGRATED NOISE,
HD2
+
BIAS TIED TO V
–90
–90
–100
–110
–120
–130
–100
–110
–120
–130
HD3
SPECTRAL DENSITY,
BIAS PIN FLOATING
SPECTRAL DENSITY,
BIAS TIED TO V
+
SINGLE ENDED INPUT
DIFFERENTIAL INPUT
SINGLE ENDED INPUT
DIFFERENTIAL INPUT
0.1
1
10
100
0.001
0.01
0.1
1
10
100
0.1
1
10
100
FREQUENCY (MHz)
FREQUENCY (MHz)
FREQUENCY (MHz)
66011 G29
66011 G27
66011 G28
Gain Error Relative to 1MHz
vs Temperature
Passband Gain and Phase
vs Temperature
% Change of fO vs Temperature
0.5
0
0.5
0
0
3
2
V
V
= 3V
ICM
S
= V
= MID-SUPPLY
OCM
–15
–30
–45
–60
–75
–90
BIAS PIN TIED TO V+
TEMPERATURES PLOTTED:
–45°C, –10°C, 25°C,
70°C, 95°C, 125°C
GAIN
–0.5
–1.0
–1.5
–2.0
–2.5
–3.0
1
PHASE
–0.5
–1.0
–1.5
–2.0
+SPECIFICATION
0
–1
–2
–3
V
V
= 3V
ICM
BIAS PIN TIED TO V+
S
–SPECIFICATION
= V
= MID-SUPPLY
OCM
TEMPERATURES PLOTTED:
–45°C, –10°C, 25°C, 70°C, 95°C, 125°C
–105
–50 –25
0
25
50
75 100 125
1
10
1
10
100
TEMPERATURE (°C)
FREQUENCY (MHz)
FREQUENCY (MHz)
66011 G30
66011 G31
66011 G32
Phase Error vs Temperature
Normalized 100Ω Resistor Trim
Normalized 125Ω Resistor Trim
1000
900
800
700
600
500
400
300
200
100
0
15
10
5
900
800
700
600
500
400
300
200
100
0
AVERAGE = 125ꢀ
STD. DEV = 0.22ꢀ
AVERAGE = 100ꢀ
STD. DEV = 0.19ꢀ
V
V
= 3V
ICM
S
= V
= MID-SUPPLY
OCM
BIAS PIN TIED TO V+
TEMPERATURES PLOTTED:
–45°C, –10°C, 25°C,
70°C, 95°C, 125°C
+SPECIFICATION
0
–5
–10
–15
–SPECIFICATION
0.99
0.994 0.998 1.002 1.006
NORMALIZED RESISTANCE
1.01
1
10
100
0.993
0.997
1.001
1.005
1.009
FREQUENCY (MHz)
NORMALIZED RESISTANCE
66011 G35
66011 G33
66011 G34
66011f
10
LTC6601-1
TYPICAL PERFORMANCE CHARACTERISTICS
Normalized Feedback 400Ω
Resistor Trim
Normalized Input 400Ω
Resistor Trim
Normalized 200Ω Resistor Trim
900
800
700
600
500
400
300
200
100
0
1000
900
800
700
600
500
400
300
200
100
0
1000
900
800
700
600
500
400
300
200
100
0
AVERAGE = 400.01ꢀ
STD. DEV = 1.0ꢀ
AVERAGE = 200ꢀ
STD. DEV = 0.37ꢀ
AVERAGE = 400.01ꢀ
STD. DEV = 0.87ꢀ
0.99
0.994 0.998 1.002 1.006
NORMALIZED RESISTANCE
1.01
0.99
0.994 0.998 1.002 1.006
NORMALIZED RESISTANCE
1.01
0.99
0.994 0.998 1.002 1.006
NORMALIZED RESISTANCE
1.01
66011 G37
66011 G36
66011 G38
Normalized 33.3pF
Capacitor Trim
Normalized 48.2pF
Capacitor Trim
Normalized 21.1pF Capacitor Trim
1200
1000
800
600
400
200
0
1200
1000
800
600
400
200
0
1000
900
800
700
600
500
400
300
200
100
0
AVERAGE = 21.1pF
STD. DEV = 0.07pF
AVERAGE = 48.2pF
STD. DEV = 0.08pF
AVERAGE = 33.3pF
STD. DEV = 0.09pF
0.984 0.990 0.997 1.003 1.009 1.015
0.992 0.995 0.998 1.001 1.004 1.007 1.010
0.988 0.993 0.999 1.005 1.010 1.016
NORMALIZED CAPACITANCE
NORMALIZED CAPACITANCE
NORMALIZED CAPACITANCE
66011 G39
66011 G41
66011 G40
Normalized 10.55pF
Capacitor Trim
Normalized 16.1pF
Capacitor Trim
Normalized 81.5pF
Capacitor Trim
350
300
250
200
150
100
50
1000
900
800
700
600
500
400
300
200
100
0
400
350
300
250
200
150
100
50
AVERAGE = 16.1pF
STD. DEV = 0.05pF
AVERAGE = 81.5pF
STD. DEV = 0.1pF
AVERAGE = 10.55pF
STD. DEV = 0.03pF
0
0
0.988 0.992 0.995 0.999 1.003 1.006 1.010 1.014
0.993 0.996 0.999 1.002 1.004 1.007 1.010
0.987 0.991 0.996 1.000 1.005 1.009 1.014
NORMALIZED CAPACITANCE
NORMALIZED CAPACITANCE
NORMALIZED CAPACITANCE
66011 G44
66011 G42
66011 G43
66011f
11
LTC6601-1
PIN FUNCTIONS (Refer to the Block Diagram)
+
+
+
IN1 , IN2 , IN4 (Pins2, 1, 20):Inputtoatrimmed100ꢀ,
C3, C4 (Pins 9, 10): Input to a trimmed 10.55pF, 21.1pF
200ꢀ,400ꢀresistorwhichfeedsanoninvertingsumming
node.Canacceptaninputsignal,befloatedortiedtoOUT .
capacitor which feeds the amplifier inverting summing
–
+
node. Typically, either float or tie to OUT . For best per-
Forbestperformance, straycapacitanceshouldbekeptas
low as possible by keeping printed circuit connections as
short and direct as possible. If necessary, strip back the
surrounding ground plane away from these pins.
formance,itishighlyrecommendedthatstraycapacitance
be kept to as low as possible by keeping printed circuit
connections as short and direct as possible, and if nec-
essary, stripping back nearby surrounding ground plane
away from these pins.
BIAS (Pin 3): Input to a three-state comparator whose
three states allow the user to tailor amplifier power. The
pin impedance appears as a 150k resistor whose default
+
–
OUT , OUT (Pins 11, 15): Output Pins. Besides driving
the internal feedback network, each pin can drive an ad-
ditional 50ꢀ to ground with typical short-circuit current
limitingof 65mA. Capacitiveloadingofthesepinsshould
be minimized by resistively decoupling the outputs from
the load with at least 25ꢀ.
–
open-circuitpotentialis1.15VwithrespecttotheV power
–
supply. IfBIASisdriventowithin0.4VoftheV supply, the
amplifier is placed into a low power shutdown, consum-
ing typically 350μA. When BIAS is floated, the amplifier
operates in its low power active state. Forcing the pin 2.3V
V
(Pin 12): Output Common Mode Reference Voltage.
OCM
ThevoltageonV
–
above V places the part into the high performance active
setstheoutputcommonmodevoltage
OCM
state. See Applications Information for more detail.
level (which is defined as the average of the voltages on
–
–
–
+
–
IN1 , IN2 , IN4 (Pins 4, 5, 6): Input to a trimmed 100ꢀ,
200ꢀ, 400ꢀ resistor which feeds an inverting summing
node. Can accept an input signal, be floated or tied to
the OUT and OUT pins). The V
pin is the midpoint
OCM
of an internal resistive voltage divider between the sup-
plies, developing a (default) mid-supply voltage potential
+
OUT . For best performance, it is highly recommended
to maximize output signal swing. The V
pin can be
OCM
that stray capacitance be kept to as low as possible by
keeping printed circuit connections as short and direct
as possible, and if necessary, stripping back nearby sur-
rounding ground plane away from these pins.
overdriven by an external voltage reference capable of
driving the input impedance presented by the V pin.
OCM
TheV
pinhasaninputresistanceofapproximately18k
OCM
to a mid-supply potential. It should be bypassed with a
highqualityceramicbypasscapacitor(forinstanceofX7R
dielectric) of at least 0.01ꢁF, (unless using symmetrical
split supplies, then connect directly to a low impedance,
lownoisegroundplane)tominimizecommonmodenoise
from being converted to differential noise by impedance
mismatches both externally and internally to the IC.
C1, C2 (Pins 7, 8): Input to a trimmed 16.1pF, 33.3pF
capacitor which feeds a noninverting summing node.
–
Typically, either float or tie to OUT . If either of these
–
pins is tied to a low impedance source other than OUT ,
a resistance of at least 25ꢀ should be placed in series.
For best performance, it is highly recommended that stray
capacitancebekepttoaslowaspossiblebykeepingprinted
circuit connections as short and direct as possible, and
if necessary, stripping back nearby surrounding ground
plane away from these pins.
66011f
12
LTC6601-1
PIN FUNCTIONS (Refer to the Block Diagram)
+
–
C5, C6 (Pins 19, 18): Input to a trimmed 16.1pF, 33.3pF
V , V (Pins 14, 13): Power Supply Pins. It is critical that
close attention be paid to supply bypassing. For single
supplyapplications(Pin13grounded), itisrecommended
that a high quality 0.1ꢁF surface mount ceramic bypass
capacitor (X7R dielectric for instance) be placed between
Pins 14 and 13, with direct short connections. Pin 13
should be tied directly to a low impedance ground plane
with minimal routing. For dual (split) power supplies, it
is recommended that at least two additional high quality
capacitor which feeds an inverting summing node. Typi-
+
cally, either float or tie to OUT . If either of these pins are
+
tied to a low impedance source other than OUT , a re-
sistance of at least 25ꢀ should be placed in series. For
best performance, it is highly recommended that stray
capacitancebekepttoaslowaspossiblebykeepingprinted
circuit connections as short and direct as possible, and if
necessary, stripping back nearby surrounding reference
plane away from these pins.
+
0.1ꢁF ceramic capacitors are used to bypass V to ground
and V to ground, again with minimal routing. For driving
large loads (< 200ꢀ), additional bypass capacitance may
beaddedforoptimalperformance.Keepinmindthatsmall
geometry (e.g., 0603) surface mount ceramic capacitors
have a much lower ESL than do leaded capacitors, and
perform best in high speed applications.
–
Exposed Pad (Pin 21): Always tie the underlying Exposed
–
Pad to V (Pin 13). If split supplies are used, do not tie
–
the pad to ground. Tie it to V .
C7, C8 (Pins 17, 16): Input to a trimmed 10.55pF, 21.1pF
capacitor which feeds the amplifier noninverting sum-
–
ming node. Typically, either float or tie to OUT . For best
performance, stray capacitance should be kept as low as
possible by keeping printed circuit connections as short
and direct as possible.If necessary, strip back the sur-
rounding ground plane away from these pins.
66011f
13
LTC6601-1
BLOCK DIAGRAM
20
IN4
19
C5
18
C6
17
C7
16
C8
+
16.1pF
33.3pF
400Ω
81.5pF
400Ω
+
200Ω
IN2
10.55pF
1
2
–
OUT
15
14
13
12
21.1pF
48.2pF
+
100Ω
–
IN1
+
V
V
V
+ 2.3V
860Ω
180k
125Ω
125Ω
–
60k
+
–
BIAS
BIAS
3
860Ω
36k
36k
180k
48.2pF
21.1pF
10.55pF
V
OCM
–
100Ω
200Ω
IN1
4
5
+
OUT
11
–
400Ω
IN2
81.5pF
33.3pF
C2
400Ω
16.1pF
–
IN4
C1
C3
C4
10
6
7
8
9
66011 BD
66011f
14
LTC6601-1
TEST CIRCUITS
20
19
18
17 16
LTC6601-1
I
L
1
2
–
25Ω
V
OUT
15
14
+
+
V
R
R
BAL
V
INP
0.1μF
–
–
0.1μF
+
–
–
BIAS
3
V
V
OUT(CM)
13
12
11
0.1μF
V
INM
+
V
BAL
OCM
3nF
I
L
4
5
+
25Ω
V
OUT
6
7
8
9
10
66011 F01
Figure 1. DC Test Circuit
20
19
18
17 16
LTC6601-1
5V
6
9 10 11 12
LT6411
1μF
1
2
–
100Ω
1μF
V
OUT
13
15
14
V
14
15
16
8
IN
COILCRAFT
TTWB-4-B
V
INP
5
+
V
0.1μF
0.1μF
1
2
3 7 17
+
–
–
50Ω
BIAS
1μF
3
V
13
12
11
0.1μF
–5V
V
OCM
3nF
V
INM
4
5
1μF
+
100Ω
V
OUT
6
7
8
9
10
66011 F02
Figure 2. AC Test Circuit (Frequency Response Testing)
66011f
15
LTC6601-1
APPLICATIONS INFORMATION
FUNCTIONAL DESCRIPTION
Figure 3 shows the basic filter architecture. The Laplace
transfer function from V to V is given by the
INDIFF
OUTDIFF
The LTC6601 is designed to make the implementation of
high frequency fully-differential filtering functions very
easy.Averylownoiseamplifierissurroundedby8precision
matched resistors and 12 precision matched capacitors
so that a myriad of filter transfer functions limited only by
possiblecombinationsandimaginationcanbeconfigured
by hard wiring pins. The amplifier itself is a wide band, low
noiseandlowdistortionfully-differentialamplifierwithac-
curateoutputphasebalancing.Itisoptimizedfordrivinglow
voltage, single-supply, differential input, analog-to-digital
converters (ADCs). The LTC6601’s outputs are capable
of swinging rail-to-rail on supplies as low as 2.7V, which
makestheamplifieridealforconvertinggroundreferenced,
following generalized equation for a 2nd order lowpass
filter:
VOUTDIFF
Gain
=
s2
V
s
INDIFF
1+
+
2
2πfO •Q
2πf
(
)
O
BothGainandQofthefilterarebasedoncomponentratios,
which match and track extremely well over temperature.
The corner frequency of the filter is a function of an RC
product. This RC product is trimmed to 1% (typical) and
is not expected to drift by more than 1% from nominal
over the entire temperature range –40°C to 85°C. As a
result, fully differential filters with tight magnitude, phase
tolerance and repeatability are achieved.
single-ended signals into V
referenced differential
OCM
signals. Unlike traditional op amps which have a single
output, the LTC6601 has two outputs to process signals
differentially. This allows for two times the signal swing
in low voltage systems when compared to single-ended
output amplifiers. The balanced differential nature of the
amplifier and matched surrounding components provide
even-order harmonic distortion cancellation, and less
susceptibility to common mode noise (like power supply
noise). The LTC6601 can be used as a single-ended input
to differential output amplifier, or as a differential input to
differential output amplifier.
Although Figure 3 implies a differential input, the LTC6601
easily accepts single-ended inputs to either input, and will
faithfully replicate the signal at the output in differential
form.
The LTC6601’s output common mode voltage, defined as
the average of the two output voltages, is independent of
theinputcommonmodevoltage, andisadjustedbyapply-
ing a voltage on the V
pin. If the pin is left open, there
OCM
is an internal resistive voltage divider, which develops a
R2
1
f
=
C2
C1
O
2π R2 • R3 • C1• C2
C2 R3
•
1
Q =
R3 C2
R2 C1
C1 R2
R1
R3
1+ 1+ GAIN
•
–
(
)
R2
R1
GAIN =
+
–
–
+
V
V
OUT(DIFF)
IN(DIFF)
R1
ꢁ
ꢄ
fO
•
6089 • 3568 • Q4 ꢀ 1788 • Q2 + 447 + 1.287 • 105 • 2 • Q2 ꢀ 1
(
)
(
)
ꢃ
ꢆ
ꢂ
ꢅ
f3dB
=
C1
C2
R2
507.6 • Q
R3
ꢁ
ꢄ
4
4
2
2
0.2236 • fO
•
2.109 • 105
•
9.891• 1012 • f3dB ꢀ 5.486 • 109 • fO + 120 • 5.526 • 109 • f3dB + 3.082 • 106 • fO
(
)
(
)
ꢃ
ꢆ
ꢂ
ꢅ
Q =
2
2
2
4
16 • fO • 8.29 • 109 • f3dB + 4.127 • 109 • fO ꢀ 6.638 • 1010 • f3dB
(
)
(
)
66011 F03
Figure 3. Basic Filter Topology and Equations
66011f
16
LTC6601-1
APPLICATIONS INFORMATION
+
–
(seetheElectricalCharacteristicstable), andcanbedriven
by an external source keeping in mind its equivalent input
impedance and equivalent input voltage. If the BIAS pin is
floated, care should be taken to control external leakage
currents to this pin to under 1ꢁA to prevent putting the
LTC6601 an undesired state.
potential halfway between the V and V pins. Whenever
this pin is not hard tied to a low impedance ground plane,
a high quality ceramic capacitor should be used to bypass
theV
pintoalowimpedancegroundplane(seeLayout
OCM
Considerations). The LTC6601’s internal common mode
feedback path forces accurate output phase balancing to
reduce even order harmonics, and centers each individual
If BIAS is tied to the positive supply, the LTC6601 dif-
ferential filter will be in a fully active state configured for
highestperformance(lowestnoiseandlowestdistortion).
If the BIAS pin is floated or left unconnected, the LTC6601
filter will be in a fully active state, with amplifier currents
reduced and performance scaled back to preserve power
consumption. If the BIAS pin is tied to the most negative
output about the potential set by the V
pin.
OCM
–
VOUT+ + VOUT
VOUTCM = VOCM
=
2
+
–
The outputs (OUT and OUT ) of the LTC6601 are capable
of swinging rail-to-rail. They can source or sink up to ap-
proximately 75mA of current. Load capacitances should
be decoupled with at least 25ꢀ of series resistance from
each output.
–
supply (V ), the LTC6601 will be placed into a low power
shutdown mode with amplifier outputs disabled. In this
state, the LTC6601 draws approximately 350μA.
Inlowpowershutdown,allinternalbiasingcurrentsources
The LTC6601 Electrical Characteristics table specifies an
inputreferredoffset.Thisspecificationactuallylumpsvolt-
+
–
areshutoff, andtheoutputpins, OUT andOUT , willeach
appear as open collectors with a non-linear capacitor in
parallel and steering diodes to either supply. The turn-on
and turn-off time constant between states are on the order
of 0.4ꢁs. Using this function to wire-OR outputs together
is not recommended.
age offsets due to offset bias currents (I ), and amplifier
OS
voltageoffsetintoonespecification.Toreferthisspecifica-
tion to the output, you simply multiply the specification
by the noise gain the LTC6601 is configured in:
V
= 1 + Gain
OSODIFF
General Design and Usage
where Gain is the closed loop gain in the particular filter
application:
As levels of integration have increased and correspond-
ingly, system supply voltages decreased, there has been
a need for ADCs to process signals differentially in order
to maintain good signal-to-noise ratios. These ADCs are
typically supplied from a single supply voltage which
can be as low as 3V (2.7V min), and will have an optimal
commonmodeinputrangenearmid-supply.TheLTC6601
makes interfacing to these ADCs easy, by providing anti-
alias filtering, single-ended to differential conversion and
common mode level shifting (translation). Figure 3 shows
a general application of this. The low frequency gain to
R2
Gain =
R1
COMPONENT INPUT PIN PROTECTION
+
–
All of the LTC6601 pins with the exception of V and V are
protected with steering diodes to either power supply. In
the event that a pin is driven beyond the supply rails, the
excesscurrentshouldbelimitedtounder10mAtoprevent
damage to the IC.
V
from V is simply:
OUTDIFF
IN
BIAS Pin
R2
R1
+
+
–
VOUTDIFF = VOUT – VOUT
≈
• V
INDIFF
The LTC6601 has a BIAS pin (Pin 3) whose function is to
tailor both performance and power of the LTC6601. The
pinhasaTheveninequivalentimpedanceofapproximately
150kꢀ to a voltage source whose potential is 1.15V above
–
Thedifferentialoutputvoltage(V
–V
)iscompletely
OUT
OUT
independent of input and output common mode voltages,
or the voltage at the common mode pin. This makes the
66011f
–
–
the V supply. This pin has fixed logic levels relative to V
17
LTC6601-1
APPLICATIONS INFORMATION
LTC6601 ideally suited for pre-amplification, level shift-
ing and conversion of single-ended signals to differential
output signals for driving differential input ADCs.
Input and Output Common Mode Voltage Range
The input common mode voltage is defined as the average
of the two inputs:
V
INP + V
INM
INPUT IMPEDANCE
V
=
INCM
2
Calculating the low frequency input impedance of the
LTC6601 depends on how the inputs are driven (whether
they are driven from a single-ended or a differential
source).
The lower limit of the input common mode range is dic-
tated by the ESD protection diodes at the input. While it
–
is possible for the inputs to swing below V , the diodes
–
will conduct if the inputs are taken a diode drop below V .
Figure 4 shows a simplified low frequency equivalent
The upper limit of the input common mode range varies
circuit of the LTC6601. For balanced input sources (V
INP
as a function of the filter configuration (GAIN), V
po-
OCM
= –V ), the low frequency input impedance is given by
INM
tential, and whether or not the inputs are single-ended or
differential. While it is possible to exceed the upper limit
of the common mode range, doing so will degrade filter
linearity. Referring to Figure 4, for linear operation, the
summing junction where R1, R2 and R3 merge together
should be prevented from swinging to within 1.4V of the
the equation:
R
= R
= R1
INP
INM
The differential input impedance is simply:
= 2 • R1
R
INDIFF
+
V power supply.
For single-ended inputs (V
= 0), the input impedance
INM
actually increases over the balanced differential case due
For the general case, the upper input common mode volt-
age limit should be constrained to:
to the fact the summing node (at the junction of R1, R2
and R3) moves in phase with V to bootstrap the input
INP
R1
R1+R2
R2
R1+R2
VOCM
•
+ V
•
INCM
≤ V+ –1.4V
impedance. Referring to Figure 4 with V
impedance looking into either input is:
= 0, the input
INM
R1
Or equivalently:
RINP =RINM
⎛
⎞
1
1– •
2
R2
⎛
⎞
R1
R2
R1
R2
⎛
⎞
V
≤ 1+
V+ −1.4V −
• VOCM
⎜
⎝
⎟
⎠
⎜
⎝
⎟
⎠
(
)
⎜
⎟
⎠
INCM
R1+R2
⎝
Thespecificationsforinputcommonmoderange(V
)
INCMR
are based on these constraints with R1 = R2 = 100Ω, and
= mid-supply. Substituting the numbers for a single
R2
R
INP
V
R1
R1
OCM
–
V
+
+
–
OUT
3V power supply, (V = 3V, V = 0V) with V
=1.5V, and
–
OCM
R3
V
INP
+
R1 = R2 = 100Ω, into the above equation, the input com-
mon mode range (V ) is between the two limits:
–
–
V
OUTDIFF
R3
INCMR
–
V
INM
+
0V ≤ V
≤ 1.7V
+
INCM
+
V
OUT
R2
R
INM
V
OCM
which is as is specified for a 3V supply.
0.1μF
66011 F04
Figure 4. Input Impedance
66011f
18
LTC6601-1
APPLICATIONS INFORMATION
Likewise, substituting the numbers for a single 5V power
pin, but must be capable of driving the input impedance of
+
–
supply, (V = 5V, V = 0V) with V
= 2.5V, and R1 = R2
the V
pin (R
). This impedance can be assumed
OCM
OCM
VOCM
= 100Ω, into the above equation, the input common mode
to be connected to a mid-supply potential. If an external
reference drives the V pin, it should still be bypassed
range (V
) is between the two limits:
INCMR
OCM
with a high quality 0.01ꢁF or higher capacitor to a low
impedance ground plane to filter any thermal noise and
to prevent common mode signals on this pin from being
inadvertently converted to differential signals.
0V ≤ V
≤ 4.7V
INCM
The output common mode voltage is defined as the aver-
age of the two outputs:
–
VOUT+ + VOUT
Noise Considerations
VOUTCM = VOCM
The V
=
2
When comparing the LTC6601 noise to other amplifiers,
be sure to compare similar specifications. Competing
devices often specify noise referred to the inputs of the
amplifier.TheinputreferredvoltagenoiseoftheLTC6601-1
is 2.1nV/√Hz. This level is one of the lowest available for
amplifiers in this speed and power range.
pin sets this average by an internal common
OCM
mode feedback loop which internally forces V + =
OUT
–V –. The output common mode range extends from
OUT
–
+
1.1 V above V to 1V below V . The V
pin sits in the
OCM
middle of a voltage divider which sets the default mid-
supply open circuit potential.
In addition to the noise generated by the amplifier, the
surrounding feedback resistors also contribute noise. A
noise model is shown in Figure 5. The output spot noise
generated by both the amplifier and the feedback compo-
nents is governed by the equation:
In single supply applications, where the LTC6601 is used
to interface to an ADC, the optimal common mode input
to the ADC is often determined by the ADC’s reference. If
the ADC makes a reference available for setting the input
common mode voltage, it can be directly tied to the V
OCM
2
2
2
2
⎛
⎞
⎟
⎛
⎜
⎝
⎞
⎟
⎠
⎛
⎝
⎞
⎛
⎞
⎛
⎝
⎞
R2
R1
R2
R1
R2
R1
R2
R1
⎛
⎝
⎞
⎛
⎝
⎞
⎛
⎞
⎛
⎝
⎞
2
2
eno = e • 1+
+ 2• I • R22 +R32 • 1+
+ 2• e
•
+ 2 enR3 • 1+
+ 2•enR2
⎜
⎜
⎟
⎠
⎜
⎟
⎠
⎜
⎝
⎟
⎠
⎜
⎜
⎟
⎠
ni
n
nR1
⎜
⎟
⎠
⎜
⎝
⎟
⎠
⎟
⎠
⎜
⎝
⎟
⎠
2
Substituting the equation for Johnson noise of a resistor (e
= 4kTR), and simplifying:
nR
2
2
2
⎛
⎞
⎟
⎛
⎜
⎝
⎞
⎟
⎠
⎛
⎞
⎟
⎠
⎛
⎞
R2
R1
R2
R1
R2
R1
R2
R1
⎛
⎞
⎛
⎝
⎞
⎛
⎝
⎞
⎛
⎝
⎞
2
eno = e • 1+
+ 2• I • R22 +R32 • 1+
+ 8 •k • T R2 1+
+R3 1+
⎜
⎜
⎜
⎟
⎠
⎜
⎟
⎠
⎜
⎟
⎠
⎜
⎟
⎠
ni
n
⎜
⎟
⎠
⎝
⎝
⎜
⎝
⎟
⎠
⎝
66011f
19
LTC6601-1
APPLICATIONS INFORMATION
2
e
nR2
R2
*
2
e
nR1
+
2
R1
I
I
n
2
2
2
e
e
e
ni
nR3
*
R3
+
–
*
*
2
e
no
nR3
R3
2
e
nR1
*
R1
–
2
n
*
2
e
nR2
R2
66011 F05
*
Figure 5. Differential Noise Model of the LTC6601
+
Table 1 lists the amplifier input referred noise for the
LTC6601-1.Tables2to10listthenoisereferredtotheinput
pinsoftheICforcommonconfigurationsoftheLTC6601-1.
To determine the spot noise at the output, simply multiply
the noise by the Gain = R2/R1. To estimate the integrated
noise at the output, multiply the noise by the gain, and the
square root of the noise bandwidth. The noise bandwidth
depends on the filter configuration. For Figure 2, the noise
bandwidth is 100MHz, or approximately 7 times the filter
bandwidth. Improvements in SNR can be made by adding
an additional RC filter at the output to band limit wide band
noise before feeding ADCs. See the section “Interfacing
the LTC6601 to ADC Converters” for more detail.
ceramic capacitor be used to bypass pin V to ground
–
and V to ground, again with minimal routing. For driv-
ing large differential loads (<200ꢀ), additional bypass
capacitance may be needed between V and V for opti-
mal performance. Note that small geometry (e.g., 0603)
surface mount ceramic capacitors have a much higher
self resonant frequency than capacitors with leads, and
perform best in high speed applications.
+
–
The V
pin should be bypassed to ground with a high
OCM
quality ceramic capacitor whose value exceeds 0.01ꢁF,
withdirect,shortconnections.Insplitsupplyapplications,
the V
pin can be either bypassed to ground or directly
OCM
hardwired to ground. Be careful not to violate the output
common mode range specifications for the V pin.
Table 1. Amplifier (Input Referred) Noise Characteristics for the
OCM
LTC6601-1
Stray parasitic capacitances to unused component pins
that set up the filter’s characteristics, should be kept to an
absoluteminimum.Thispreventsdeviationsfromtheideal
frequencyresponse. Anideallayouttechniquewouldbeto
remove the solder pads for the unused component pins,
and strip away the ground plane underneath these pins to
lowercapacitancetoanabsoluteminimum.Floatingunused
component pins which set up the filter characteristics will
not reduce the reliability of the LTC6601.
+
BIAS PIN PULLED TO V
BIAS PIN FLOATING
e
i
e
i
n
ni
n
ni
nV/√Hz
pA/√Hz
nV/√Hz
pA/√Hz
2.1
3
2.6
2.1
LAYOUT CONSIDERATIONS
Because the LTC6601 is a very high speed amplifier, it is
sensitive to both stray capacitance and stray inductance.
It is critical that close attention be paid to supply bypass-
ing. For single supply applications, it is recommended
that a high quality 0.1ꢁF surface mount ceramic bypass
capacitor be placed between Pins 14 and 13 with direct
short connections. Pin 13 and the Exposed Pad, Pin 21,
should be tied directly to a low impedance ground plane
with minimal routing. For dual (split) power supplies, it
is recommended that an additional high quality, 0.1ꢁF
Attheoutput,alwayskeepinmindthedifferentialnatureof
theLTC6601, andthatitiscriticalthattheloadimpedances
seenbybothoutputs(strayorintended), shouldbeasbal-
anced and symmetric as possible. This will help preserve
the natural balance of the LTC6601, which minimizes the
generation of even order harmonics and preserves the
rejection of common mode signals and noise.
66011f
20
LTC6601-1
APPLICATIONS INFORMATION
INTERFACING THE LTC6601 TO ADC CONVERTERS
often be much greater than that of the LTC6601, so hav-
ing this discrete RC filter will give the additional benefit
of band limiting broadband output noise.
TheLTC6601’srail-to-raildifferentialoutputandadjustable
output common mode voltage make the LTC6601 ideal
for interfacing to low voltage, single supply, differential
input ADCs. The sampling process of ADCs creates a
sampling transient that is caused by the switching-in
of the ADC sampling capacitor. The switching-in of this
samplingcapacitormomentarily“shorts”theoutputofthe
amplifier as charge is transferred between amplifier and
sampling capacitor. The amplifier must recover and settle
from this load transient before this acquisition period has
ended, for a valid representation of the input signal. The
LTC6601 will settle much more quickly from these peri-
odic load impulses than it does from a 2V input step, but
it is a good idea to add an RC network after the outputs
of the LTC6601 to decouple the sampling transient of the
ADC (See Figure 6). The capacitance of the decoupling
network serves to provide the bulk of the charge during
the sampling process, while the two resistors of the filter
network are used to dampen and attenuate any transient
induced by the ADC. The ADC’s sampling bandwidth will
The selection of the RC time constant is trial and error
for a given ADC, but the following guidelines are recom-
mended. Choose an RC pole frequency greater than the
cutoff frequency of the LTC6601. 80MHz RC filters are
good for filtering broadband noise. Lower frequency RC
filters improve SNR at the expense of settling time. The
resistorsinthedecouplingnetworkshouldbeatleast25ꢀ.
Too much resistance in the decoupling network leaves
insufficient settling time and will create a voltage divider
between the dynamic input impedance of the ADC and the
decoupling resistors. Using insufficient resistance might
prevent proper dampening of the load transient caused by
the sampling process, and prolong the time required for
settling. In 16-bit applications, this will typically require
a minimum of 11 RC time constants. It is recommended
that the capacitor is chosen with low dielectric absorption
(such as a C0G multilayer ceramic capacitor).
20
19
18
17 16
LTC6601-1
C1
1
2
–
R
V
OUT
15
14
+
CONTROL
V
IN
3V
–
0.1μF
D15
+
–
•
•
+
–
A
A
IN
IN
1μF
BIAS
3
D0
C2
C1
13
12
3.3V
1μF
V
GND
CM
1μF
V
OCM
10nF
2.2μF
4
5
+
R
V
OUT
11
66011 F06
t = R • (C1 + 2 • C2)
6
7
8
9
10
Figure 6. Interfacing the LTC6601 to A/D Converters
66011f
21
LTC6601-1
APPLICATIONS INFORMATION
A GALLERY OF BASIC FILTER TOPOLOGIES
these topologies range from 1V/V to 7V/V. The Qs listed
are within the range of 0.54 and 1.72. The f s listed are
O
Tables2through10list(sortedbyGain)ahundredpossible
filter topologies that can be easily implemented with the
LTC6601. The tables also list the LTC6601-1 approximate
in the range of 6.96MHz and 22.71MHz, and the –3dB
frequencies listed range from 5.5MHz to 27.5MHz. For
all filters listed, R3 = 125ꢀ. Figures 7 to 10 show how to
pin-strap each filter configuration.
midband (1MHz) spot noise e referred to the input re-
in
+
sistor, R1 (with the BIAS pin pulled to V ). The gains for
Table 2. Gain of 7 Filter Configurations
GAIN
e
in
V/V
7.0
7.0
7.0
7.0
dB
f (MHz)
f
(MHz)
–3dB
Q
R1 (Ω)
57.14
57.14
57.14
57.14
R2 (Ω)
400.00
400.00
400.00
400.00
C1 (pF)
48.2
C2 (pF)
97.6
(nV/√Hz)
O
16.902
16.902
16.902
16.902
10.38
9.57
8.96
8.12
7.43
0.539
0.771
1.175
0.656
3.7
10.36
12.10
7.49
48.2
114.8
130.9
130.9
3.7
48.2
3.7
58.75
3.7
Table 3. Gain of 6 Filter Configurations
GAIN
e
in
V/V
6.0
6.0
6.0
6.0
6.0
dB
f (MHz)
f
(MHz)
Q
R1 (Ω)
66.67
66.67
66.67
66.67
66.67
R2 (Ω)
400.00
400.00
400.00
400.00
400.00
C1 (pF)
48.2
C (pF)
(nV/√Hz)
O
–3dB
2
15.563
15.563
15.563
15.563
15.563
10.38
9.57
8.67
8.12
7.47
10.03
12.52
7.67
0.684
1.071
0.634
0.870
0.592
97.6
114.8
114.8
130.9
130.9
3.8
48.2
3.8
58.75
58.75
69.3
3.8
9.59
3.8
6.07
3.8
Table 4. Gain of 5 Filter Configurations
GAIN
e
in
V/V
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
dB
f (MHz)
f
(MHz)
–3dB
Q
R1 (Ω)
80.00
80.00
80.00
80.00
80.00
80.00
80.00
80.00
R2 (Ω)
400.00
400.00
400.00
400.00
400.00
400.00
400.00
400.00
C1 (pF)
48.2
C2 (pF)
81.5
nV/√Hz
o
13.979
13.979
13.979
13.979
13.979
13.979
13.979
13.979
11.36
10.38
9.40
8.67
8.12
7.98
7.47
6.96
9.67
12.78
7.67
0.614
0.936
0.594
0.849
1.290
0.591
0.779
0.579
4.0
48.2
97.6
4.0
58.75
58.75
58.75
69.3
97.6
4.0
10.07
11.25
6.46
114.8
130.9
114.8
130.9
130.9
4.0
4.0
4.0
8.16
69.3
4.0
5.50
79.85
4.0
66011f
22
LTC6601-1
APPLICATIONS INFORMATION
Table 5. Gain of 4 Filter Configurations
GAIN
e
in
V/V
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
dB
f (MHz)
f
MHz
–3dB
Q
R1 (Ω)
100.00
100.00
100.00
100.00
100.00
100.00
100.00
100.00
100.00
R2 (Ω)
400.00
400.00
400.00
400.00
400.00
400.00
400.00
400.00
400.00
C1 (pF)
48.2
C2 (pF)
81.5
nV/√Hz
O
12.041
12.041
12.041
12.041
12.041
12.041
12.041
12.041
12.041
11.36
10.38
9.40
8.67
8.65
7.98
7.43
7.47
6.96
13.05
0.834
1.480
0.799
1.284
0.575
0.794
0.596
1.141
0.775
4.2
14.80
10.47
12.00
6.76
48.2
97.6
4.2
58.75
58.75
69.3
97.6
4.2
114.8
97.6
4.2
4.2
8.84
69.3
114.8
114.8
130.9
130.9
4.2
6.09
79.85
69.3
4.2
10.00
7.57
4.2
79.85
4.2
Table 6. Gain of 3 Filter Configurations
GAIN
e
in
V/V
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
dB
f (MHz)
f
(MHz)
–3dB
Q
R1 (Ω)
66.67
R2 (Ω)
200.00
200.00
200.00
200.00
200.00
400.00
200.00
200.00
400.00
200.00
400.00
400.00
400.00
400.00
400.00
400.00
200.00
C1 (pF)
48.2
C2 (pF)
81.5
(nV/√Hz)
O
9.542
9.542
9.542
9.542
9.542
9.542
9.542
9.542
9.542
9.542
9.542
9.542
9.542
9.542
9.542
9.542
9.542
16.06
14.68
13.53
13.29
12.26
11.36
11.48
11.29
10.29
10.57
9.40
12.36
0.568
0.763
1.091
0.554
0.715
1.300
0.928
0.552
0.763
0.674
1.224
0.788
0.601
1.212
0.825
1.172
0.544
4.3
15.74
17.83
9.88
66.67
48.2
97.6
4.3
66.67
48.2
114.8
97.6
4.3
66.67
58.75
58.75
48.2
4.3
12.39
15.77
14.07
8.34
66.67
114.8
81.5
4.3
133.33
66.67
4.6
58.75
69.3
130.9
114.8
81.5
4.3
66.67
4.3
11.04
10.06
12.85
9.54
133.33
66.67
58.75
69.3
4.6
130.9
97.6
4.3
133.33
133.33
133.33
133.33
133.33
133.33
66.67
58.75
69.3
4.6
8.65
97.6
4.6
8.06
6.69
79.85
69.3
97.6
4.6
7.98
10.88
8.48
114.8
114.8
130.9
130.9
4.6
7.43
79.85
79.85
79.85
4.6
6.96
9.40
4.6
9.85
7.13
4.3
66011f
23
LTC6601-1
APPLICATIONS INFORMATION
Table 7. Gain of 2 Filter Configurations
GAIN
e
in
V/V
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.0
dB
f (MHz)
f
(MHz)
–3dB
Q
R1 (Ω)
100.00
100.00
100.00
100.00
100.00
100.00
100.00
200.00
100.00
100.00
200.00
100.00
200.00
200.00
200.00
200.00
R2 (Ω)
200.00
200.00
200.00
200.00
200.00
200.00
200.00
400.00
200.00
200.00
400.00
200.00
400.00
400.00
400.00
400.00
C1 (pF)
48.2
C2 (pF)
81.5
(nV/√Hz)
O
6.021
6.021
6.021
6.021
6.021
6.021
6.021
6.021
6.021
6.021
6.021
6.021
6.021
6.021
6.021
6.021
16.06
14.55
14.68
13.29
12.24
12.26
11.29
10.29
10.51
10.57
9.47
18.95
0.868
0.626
1.323
0.840
0.640
1.200
0.835
1.197
0.660
1.102
0.796
0.819
0.616
1.254
0.864
1.341
5.0
12.69
20.46
15.34
10.96
16.66
12.98
13.97
9.76
58.75
48.2
81.5
5.0
97.6
5.0
58.75
69.3
97.6
5.0
97.6
5.0
58.75
69.3
114.8
114.8
81.5
5.0
5.0
58.75
79.85
69.3
5.5
114.8
130.9
81.5
5.0
13.97
10.52
11.17
7.55
5.0
69.3
5.5
9.85
79.85
79.85
69.3
130.9
81.5
5.0
8.82
5.5
8.65
11.91
9.48
97.6
5.5
8.06
79.85
79.85
97.6
5.5
7.43
10.40
114.8
5.5
Table 8. Gain of 1.667 Filter Configurations
GAIN
e
in
V/V
dB
f (MHz)
O
f
MHz
–3dB
Q
R1 (Ω)
80.00
80.00
80.00
80.00
80.00
80.00
80.00
80.00
80.00
R2 (Ω)
133.33
133.33
133.33
133.33
133.33
133.33
133.33
133.33
133.33
C1 (pF)
48.2
C2 (pF)
81.5
nV/√Hz
1.667
1.667
1.667
1.667
1.667
1.667
1.667
1.667
1.667
4.437
4.437
4.437
4.437
4.437
4.437
4.437
4.437
4.437
19.67
17.97
16.57
16.28
15.01
14.33
13.82
12.94
12.06
19.35
22.12
23.16
15.60
17.80
18.58
13.19
14.77
11.32
0.696
0.934
1.336
0.679
0.875
1.046
0.676
0.826
0.666
5.1
48.2
97.6
5.1
48.2
114.8
97.6
5.1
58.75
58.75
58.75
69.3
5.1
114.8
126
5.1
5.1
114.8
130.9
130.9
5.1
69.3
5.1
79.85
5.1
66011f
24
LTC6601-1
APPLICATIONS INFORMATION
Table 9. Gain of 1.333 Filter Configurations
GAIN
e
in
V/V
dB
f (MHz)
O
f
MHz
–3dB
Q
R1 (Ω)
100.00
100.00
100.00
100.00
100.00
100.00
100.00
100.00
100.00
100.00
100.00
R2 (Ω)
133.33
133.33
133.33
133.33
133.33
133.33
133.33
133.33
133.33
133.33
133.33
C1 (pF)
48.2
C2 (pF)
81.5
nV/√Hz
1.333
1.333
1.333
1.333
1.333
1.333
1.333
1.333
1.333
1.333
1.333
2.499
2.499
2.499
2.499
2.499
2.499
2.499
2.499
2.499
2.499
2.499
19.67
17.82
17.97
16.28
14.99
15.01
14.06
13.82
12.88
12.94
12.06
22.73
0.841
0.633
1.185
0.818
0.646
1.097
1.506
0.814
0.663
1.025
0.801
5.7
15.77
24.34
18.44
13.58
19.82
20.12
15.61
12.03
16.64
13.45
58.75
48.2
81.5
5.7
97.6
5.7
58.75
69.3
97.6
5.7
97.6
5.7
58.75
58.75
69.3
114.8
130.9
114.8
114.8
130.9
130.9
5.7
5.7
5.7
79.85
69.3
5.7
5.7
79.85
5.7
Table 10. Gain of 1 Filter Configurations
GAIN
e
in
V/V
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
dB
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
f (MHz)
f
MHz
–3dB
Q
R1 (Ω)
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
200.0
100.0
100.0
200.0
100.0
200.0
200.0
200.0
200.0
200.0
400.0
400.0
400.0
R2 (Ω)
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
100.0
200.0
100.0
100.0
200.0
100.0
200.0
200.0
200.0
200.0
200.0
400.0
400.0
400.0
C1 (pF)
48.2
C2 (pF)
81.5
nV/√Hz
6.4
6.4
6.4
6.4
6.4
6.4
6.4
6.4
6.4
6.9
6.4
6.4
6.9
6.4
6.9
6.9
6.9
6.9
6.9
7.9
7.9
7.9
O
22.71
20.75
20.57
19.14
18.80
17.31
17.33
16.23
15.96
14.55
14.87
14.95
13.39
13.92
12.48
12.24
11.40
11.29
10.51
9.47
25.40
27.23
17.86
27.50
20.62
15.35
22.15
22.58
17.45
19.09
13.57
18.59
14.90
15.04
11.38
16.25
13.27
16.47
14.17
13.26
10.86
11.57
0.804
1.079
0.623
1.543
0.784
0.634
1.011
1.312
0.781
1.079
0.650
0.954
0.798
0.769
0.650
1.115
0.850
1.715
1.167
1.350
0.935
1.535
48.2
97.6
58.75
48.2
81.5
114.8
97.6
58.75
69.3
97.6
58.75
58.75
69.3
114.8
130.9
114.8
81.5
58.75
79.85
69.3
114.8
130.9
81.5
69.3
79.85
79.85
69.3
130.9
81.5
97.6
79.85
69.3
97.6
114.8
114.8
81.5
79.85
69.3
8.82
79.85
79.85
81.5
8.06
97.6
66011f
25
LTC6601-1
APPLICATIONS INFORMATION
20
19
18
17
16
20
19
18
17
16
LTC6601-1
LTC6601-1
1
2
15
11
1
2
15
11
+
+
R1
57.14W
R1
66.66W
4
5
4
5
–
–
6
7
8
9
10
16
6
7
8
9
10
16
20
19
18
17
20
19
18
17
LTC6601-1
LTC6601-1
1
2
15
11
1
2
15
11
+
+
R1
80Ω
R1
100Ω
4
5
4
5
–
–
6
7
8
9
10
16
6
7
8
9
10
16
20
19
18
17
20
19
18
17
LTC6601-1
LTC6601-1
1
2
15
11
1
2
15
11
+
+
R1
133.33Ω
R1
200Ω
4
5
4
5
–
–
6
7
8
9
10
6
7
8
9
10
20
19
18
17
16
LTC6601-1
1
15
11
+
2
R1
400Ω
4
5
–
66011 F07
6
7
8
9
10
Figure 7. Pin-Strap Hookup for a Particular R1
66011f
26
LTC6601-1
APPLICATIONS INFORMATION
20
19
18
17
16
20
19
18
17
16
LTC6601-1
LTC6601-1
1
2
15
1
2
15
11
+
+
R2
100Ω
R2
133Ω
4
5
4
5
–
–
11
6
7
8
9
10
16
6
7
8
9
10
16
20
19
18
17
20
19
18
17
LTC6601-1
LTC6601-1
1
2
15
11
1
2
15
11
+
+
R2
200Ω
R2
400Ω
4
5
4
5
–
–
66011 F08
6
7
8
9
10
6
7
8
9
10
Figure 8. Pin-Strap Hookup for a Particular R2
20
19
18
17
16
20
19
18
17
16
LTC6601-1
LTC6601-1
1
2
15
11
1
2
15
11
+
+
C1
48.2pF
C1
58.75pF
4
5
4
5
–
–
6
7
8
9
10
16
6
7
8
9
10
16
20
19
18
17
20
19
18
17
LTC6601-1
LTC6601-1
1
2
15
11
1
2
15
11
+
+
C1
69.3pF
C1
79.85pF
4
5
4
5
–
–
6
7
8
9
10
6
7
8
9
10
66011 F09
Figure 9. Pin-Strap Hookup for a Particular C1
66011f
27
LTC6601-1
APPLICATIONS INFORMATION
20
19
18
17
16
20
19
18
17
16
LTC6601-1
LTC6601-1
1
2
15
1
2
15
11
+
+
C2
81.5pF
C2
114.8pF
4
5
4
5
–
–
11
6
7
8
9
10
16
6
7
8
9
10
16
20
19
18
17
20
19
18
17
LTC6601-1
LTC6601-1
1
2
15
11
1
2
15
11
+
+
C2
97.6pF
C2
130.9pF
4
5
4
5
–
–
6
7
8
9
10
6
7
8
9
10
66011 F10
Figure 10. Pin-Strap Hookup for a Particular C2
66011f
28
LTC6601-1
APPLICATIONS INFORMATION
Example Filter Configurations of Basic 2nd Order
Filters
Figure 11 shows some simplified component hookups of
a selection of filters taken from Tables 7, 9 and 10. For
simplicity, V
pin bypass and power supply bypass
OCM
are not shown.
20
19
18
17
16
20
19
18
17
16
LTC6601-1
LTC6601-1
1
2
15
11
1
2
15
11
+
+
V
V
V
V
V
V
V
V
V
V
V
V
IN
IN
IN
OUT(DIFF)
OUT(DIFF)
OUT(DIFF)
IN
IN
IN
OUT(DIFF)
4
5
4
5
–
–
6
7
8
9
10
16
6
7
8
9
10
16
GAIN = 0dB
= 13.92MHz
GAIN = 0dB
f = 22.71MHz
O
Q = 0.804
f
O
Q = 0.769
20
19
18
17
20
19
18
17
LTC6601-1
LTC6601-1
1
2
15
11
1
2
15
11
+
+
OUT(DIFF)
4
5
4
5
–
–
6
7
8
9
10
16
6
7
8
9
10
16
GAIN = 6dB
= 9.85MHz
GAIN = 6dB
f = 16.06MHz
O
Q = 0.868
f
O
Q = 0.819
20
19
18
17
20
19
18
17
LTC6601-1
LTC6601-1
1
2
15
11
1
2
15
11
+
+
OUT(DIFF)
4
5
4
5
–
–
6
7
8
9
10
6
7
8
9
10
66011 F11
GAIN = 2.5dB
= 12.06MHz
GAIN = 2.5dB
f = 19.67MHz
O
Q = 0.841
f
O
Q = 0.801
Figure 11. Basic 2nd Order Filter Configurations
66011f
29
LTC6601-1
APPLICATIONS INFORMATION
Figure 12 shows some simplified component hookups
of a selection of filters taken from Tables 4, 5, and 6. For
simplicity, V
pin bypass and power supply bypass
OCM
are not shown.
20
19
18
17
16
20
19
18
17
16
LTC6601-1
LTC6601-1
1
2
15
11
1
2
15
11
+
+
V
V
V
V
V
V
V
V
V
V
V
V
IN
IN
IN
OUT(DIFF)
OUT(DIFF)
OUT(DIFF)
IN
IN
IN
OUT(DIFF)
4
5
4
5
–
–
6
7
8
9
10
16
6
7
8
9
10
16
GAIN = 12dB
= 6.96MHz
GAIN = 12dB
f = 11.36MHz
O
Q = 0.834
f
O
Q = 0.775
20
19
18
17
20
19
18
17
LTC6601-1
LTC6601-1
1
2
15
11
1
2
15
11
+
+
OUT(DIFF)
4
5
4
5
–
–
6
7
8
9
10
16
6
7
8
9
10
16
GAIN = 14dB
= 6.96MHz
GAIN = 14dB
f = 11.36MHz
O
Q = 0.614
f
O
Q = 0.579
20
19
18
17
20
19
18
17
LTC6601-1
LTC6601-1
1
2
15
11
1
2
15
11
+
+
OUT(DIFF)
4
5
4
5
–
–
6
7
8
9
10
6
7
8
9
10
66011 F12
GAIN = 9.54dB
= 9.85MHz
GAIN = 9.54dB
f = 16.06MHz
O
Q = 0.568
f
O
Q = 0.544
Figure 12. Basic 2nd Order Filter Configurations
66011f
30
LTC6601-1
APPLICATIONS INFORMATION
COMPLEX FILTER CONFIGURATIONS
Figures 15 to 17 show additional circuits highlighting the
useofR4inthemodifiedsecondordercicuittosetthef
3dB
A Modified 2nd Order Lowpass Filter Topology
frequency to 7.5MHz, 10MHz and 15MHz respectively.
The basic filter topology of Figure 3 can be modified as
shown in Figure 13. The Figure 13 circuit includes an
impedance path between the two summing nodes (the
circuit nodes common to resistors R1, R2 and R3). A
resistor and/or a capacitor connection between the sum-
ming nodes provide even more flexibility, and enhance
The design procedure for a specified f
as follows:
frequency is
3dB
1 Using the chosen C1, C2 and C3 values calculate the
f value.
O
2. Using f of step 1 and the specified f
calculate the
3dB
O
the filter design options (the f and Q equations shown
Q value.
O
in Figure 13 reduce to equations of Figure 3 if C3 is zero
and R4 is infinite).
3. Calculate the R4 value using the Q value of step 3.
4. Calculate the required external resistor R value for
EXT
The modified second order filter topology provides for
the R4 value in step 3. Example, in Figure 14 the Q
setting the Q value (with R4) without changing the f
O
value for f = 5MHz is 0.54, the required R4 resistor
3dB
value and increasing the passband gain to greater than
one without changing the Q value (in the Q equation of
Figure 13 the value of Q does not change if the value of
the [1 + GAIN + 2(R2/R4)] denominator factor does not
change). Using R4 to set the Q value allows the option
is 350ꢀ, the R4A and R4B resistors are the internal
100ꢀ and the R resistor is 150ꢀ [R = R4 – (R4A
EXT
EXT
+ R4B)].
Note: The modified second order filter topology requires
the use of at least two of the three input resistor pairs (two
of the three 400ꢀ, 200ꢀ and 100ꢀ pairs).
to design the –3dB frequency (f ). If the Q value varies
3dB
and the f value is constant then the f
ies in a second order lowpass function (refer to the f
frequency var-
O
3dB
3dB
equation of Figure 13).
Figure 14 shows three configurations using a capacitor
(C3) and a resistor (R4) between the summing nodes.
The external 49.9ꢀ resistor isolates the LTC6601 outputs
from driving directly a capacitive load. The three circuits
of Figure 14 have equal f and Q values and differ only in
O
the passband gain. The 150ꢀ R4 resistor sets a Q value
equal to 0.54 for an f = 5MHz for f = 6.954MHz.
3dB
O
66011f
31
LTC6601-1
APPLICATIONS INFORMATION
R2
C2
C1
R1
R3
R4A
+
–
C3A
–
+
V
R
IN(DIFF)
EXT
V
49.9Ω
C3B
OUT(DIFF)
R4B
C1
C2
R1
R3
R2
66011 F13
R4 = R4A + R4B + R
C3 = C3A || C3B
EXT
ꢁ
ꢄ
fO
•
6089 • 3568 • Q4 ꢀ 1788 • Q2 + 447 + 1.287 • 105 • 2 • Q2 ꢀ 1
(
)
(
)
ꢃ
ꢆ
ꢂ
ꢅ
f3dB
=
507.6 • Q
ꢁ
ꢄ
4
2
0.2236 • fO
•
2.109 • 105
•
9.891• 1012 • f3dB4 ꢀ 5.486 • 109 • fO + 120 • 5.526 • 109 • f3dB2 + 3.082 • 106 • fO
(
)
(
)
ꢃ
ꢆ
ꢂ
ꢅ
Q =
2
2
4
16 • fO • 8.29 • 109 • f3dB2 + 4.127 • 109 • fO ꢀ 6.638 • 1010 • f3dB
(
)
(
)
1.25 • 104 • C1• Q • R2
R4 =
ꢁ C2 + 2 • C3ꢄ
559 • C1• R2 •
ꢀ 50 • Q • C1• 125 • GAIN + R2 + 125 ꢀ C2 • R2
ꢆ
ꢅ
(
)
(
)
ꢃ
ꢂ
C1
GAIN
R2 • R3 • C1• C2 + 2 • C3
VOUT(DIFF)
(
)
= –
V
R1• R2 • 2 •R3 + R4 + R3 • R4 + R2 • R3 • R4
(
)
IN(DIFF)
(
)
1
S2
+
• S +
R1•R2 •R3 •R4 • C2 + 2 • C3
R2 • R3 • C1• C2 + 2 • C3
(
)
(
)
VOUT(DIFF)
R2
R1
GAIN = –
= –
V
IN(DIFF)
ꢁR3ꢄ
ꢂR2ꢅ
ꢁ C2
ꢂ C1
C3ꢄ
C1ꢅ
•
+ 2 •
ꢃ
ꢆ
ꢃ
ꢆ
1
fO
=
Q =
ꢁ
R2ꢄ R3 C2
R4ꢅ R2 C1
2 • ꢀ • R2 •R3 • C1• C2 + 2 • C3
(
)
1+ 1+|GAIN|+2•
•
ꢆ
–
ꢃ
ꢂ
Figure 13. Modified Filter Topology and Equations
66011f
32
LTC6601-1
APPLICATIONS INFORMATION
20
19
18
17
16
20
19
18
17
16
LTC6601-1
LTC6601-1
75Ω
75Ω
1
2
15
1
2
15
11
+
+
V
V
IN
20Ω
150Ω
V
20Ω
V
OUT(DIFF)
IN
OUT(DIFF)
4
5
4
5
–
–
11
6
7
8
9
10
6
7
8
9
10
GAIN = 1
= 6.954MHz
GAIN = 2.3
f = 6.964MHz
O
Q = 0.54
f = 5MHz
–3dB
f
O
Q = 0.54
= 5MHz
f
–3dB
20
19
18
17
16
LTC6601-1
75Ω
75Ω
1
2
15
11
+
V
20Ω
V
OUT(DIFF)
IN
4
5
–
6
7
8
9
10
66011 F14a
GAIN = 3.3
= 6.964MHz
f
O
Q = 0.54
= 5MHz
f
–3dB
Gain Magnitude vs Frequency (Gain = 1)
10
Passband Phase and Group Delay
30
PHASE
0
–30
0
–10
–20
–30
–40
–50
–60
–60
–90
–120
50
40
30
20
10
0
GROUP DELAY
0
100k
1M
10M
100M
100k
2M
4M
6M
8M
10M
FREQUENCY (Hz)
FREQUENCY (Hz)
66011 F14b
66011 F14c
Figure 14. Modified Filter Configuration Using a Capacitor and a Resistor Between Summing Nodes (f–3dB = 5MHz)
66011f
33
LTC6601-1
APPLICATIONS INFORMATION
20
19
18
17
16
20
19
18
17
16
12.4Ω
= 225
LTC6601-1
LTC6601-1
1
2
15
1
2
15
11
+
+
V
Z
V
Z
IN
IN(DIFF)
IN
IN(DIFF)
24.9Ω
V
V
OUT(DIFF)
= 800
OUT(DIFF)
4
5
4
5
–
–
12.4Ω
11
6
7
8
9
10
6
7
8
9
10
GAIN = 1
= 7.971MHz
GAIN = 3.56
f = 7.971MHz
O
Q = 0.67
f = 7.5MHz
–3dB
f
O
Q = 0.67
= 7.5MHz
f
–3dB
20
19
18
17
16
LTC6601-1
12.4Ω
1
2
15
11
+
V
IN
V
Z
= 175.6
12.4Ω
OUT(DIFF)
IN(DIFF)
4
5
–
6
7
8
9
10
66011 F15a
GAIN = 4.55
= 7.971MHz
f
O
Q = 0.67
= 7.5MHz
f
–3dB
Gain Magnitude vs Frequency (Gain = 1)
10
Passband Phase and Group Delay
30
PHASE
0
–30
0
–10
–20
–30
–40
–50
–60
–60
–90
–120
50
40
30
20
10
0
GROUP DELAY
0
100k
1M
10M
100M
100k
2M
4M
6M
8M
10M
FREQUENCY (Hz)
FREQUENCY (Hz)
66011 F15b
66011 F15c
Figure 15. Modified Filter Configuration Using a Resistor Between Summing Nodes (f–3dB = 7.5MHz)
66011f
34
LTC6601-1
APPLICATIONS INFORMATION
20
19
18
17
16
20
19
18
17
16
24.9Ω
LTC6601-1
LTC6601-1
1
2
15
1
2
15
11
+
+
V
Z
IN
IN(DIFF)
V
IN
V
V
49.9Ω
= 250
OUT(DIFF)
OUT(DIFF)
Z
= 400
IN(DIFF)
4
5
4
5
–
–
24.9Ω
11
6
7
8
9
10
6
7
8
9
10
GAIN = 0
= 11.27MHz
GAIN = 1.6
f = 11.27MHz
O
Q = 0.64
f = 10MHz
–3dB
f
O
Q = 0.64
= 10MHz
f
–3dB
20
19
18
17
16
LTC6601-1
1
2
15
11
24.9Ω
24.9Ω
+
V
Z
IN
IN(DIFF)
V
OUT(DIFF)
= 164
4
5
–
6
7
8
9
10
66011 F16a
GAIN = 2.6
= 11.27MHz
f
O
Q = 0.64
= 10MHz
f
–3dB
Gain Magnitude vs Frequency (Gain = 1)
10
Passband Phase and Group Delay
30
0
PHASE
0
–10
–20
–30
–40
–50
–30
–60
–90
–120
50
40
30
20
10
0
GROUP DELAY
0
100k
4M
8M
12M
16M
20M
100k
1M
10M
100M
FREQUENCY (Hz)
FREQUENCY (Hz)
66011 F16c
66011 F16b
Figure 16. Modified Filter Configuration Using a Resistor Between Summing Nodes (f–3dB = 10MHz)
66011f
35
LTC6601-1
APPLICATIONS INFORMATION
20
19
18
17
16
20
19
18
17
16
LTC6601-1
LTC6601-1
24.9Ω
1
2
15
1
2
15
11
+
+
V
V
IN
IN(DIFF)
IN
49.9Ω
V
V
OUT(DIFF)
Z
= 400
OUT(DIFF)
Z
= 250
IN(DIFF)
4
5
4
5
–
–
24.9Ω
11
6
7
8
9
10
6
7
8
9
10
GAIN = 1
= 16.04MHz
GAIN = 1.6
f = 16.04MHz
O
Q = 0.66
f = 15MHz
–3dB
f
O
Q = 0.56
= 15MHz
f
–3dB
20
19
18
17
16
LTC6601-1
1
2
15
11
24.9Ω
24.9Ω
+
V
Z
IN
IN(DIFF)
V
OUT(DIFF)
= 164
4
5
–
6
7
8
9
10
66011 F17a
GAIN = 2.6
= 16.04MHz
f
O
Q = 0.66
= 15MHz
f
–3dB
Gain Magnitude vs Frequency (Gain = 1)
10
Passband Phase and Group Delay
30
0
PHASE
0
–10
–20
–30
–40
–50
–30
–60
–90
–120
50
40
30
20
10
0
GROUP DELAY
0
100k
1M
10M
100M
100k
4M
8M
12M
16M
20M
FREQUENCY (Hz)
FREQUENCY (Hz)
66011 F17b
66011 F17c
Figure 17. Modified Filter Configuration Using a Resistor Between Summing Nodes (f–3dB = 15MHz)
66011f
36
LTC6601-1
APPLICATIONS INFORMATION
DC1251A Demonstration Board
additional filtering (a lowpass filter up to a 5th order can
be implemented with a DC1251A demonstration circuit).
The DC1251A has SMA connectors for the differential
input and output of the LTC6601-1. An on board 106MHz
lowpass RC filters the LTC6601-1 output.
TheDC1251AdemonstrationcircuitcontainsanLTC6601-1
(DC1251A-A).OnaDC1251AtheLTC6601-1programming
pins can be connected through 0603 resistor jumpers. In
addition, optionalsurfacemountcapacitorsandinductors
at the LTC6601 input and/or output can be installed for
DC12351A Top Silk Screen
66011f
37
LTC6601-1
APPLICATIONS INFORMATION
66011f
38
LTC6601-1
PACKAGE DESCRIPTION
UF Package
20-Lead Plastic QFN (4mm × 4mm)
(Reference LTC DWG # 05-08-1710)
0.70 p0.05
4.50 p 0.05
3.10 p 0.05
2.45 p 0.05
(4 SIDES)
PACKAGE OUTLINE
0.25 p0.05
0.50 BSC
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
BOTTOM VIEW—EXPOSED PAD
PIN 1 NOTCH
R = 0.30 TYP
R = 0.115
TYP
0.75 p 0.05
4.00 p 0.10
(4 SIDES)
19 20
0.38 p 0.10
PIN 1
TOP MARK
(NOTE 6)
1
2
2.45 p 0.10
(4-SIDES)
(UF20) QFN 10-04
0.200 REF
0.25 p 0.05
0.50 BSC
0.00 – 0.05
NOTE:
1. DRAWING IS PROPOSED TO BE MADE A JEDEC PACKAGE OUTLINE MO-220
VARIATION (WGGD-1)—TO BE APPROVED
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION
ON THE TOP AND BOTTOM OF PACKAGE
66011f
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
39
LTC6601-1
TYPICAL APPLICATION
4th Order, 10MHz, Lowpass Filter with 12dB Gain
20
19
18
17
16
20
19
18
17
16
LTC6601-1
LTC6601-1
1
2
15
11
1
2
15
+
+
V
IN
V
49.9Ω
49.9Ω
OUT(DIFF)
Z
= 200
IN(DIFF)
4
5
4
5
–
–
11
6
7
8
9
10
6
7
8
9
10
66011 TA02a
Gain Magnitude vs Frequency
20
0
–20
–40
–60
–80
–100
100k
1M
10M
100M
FREQUENCY (Hz)
66011 TA02b
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
Up to 10MHz Filters, SNR = 92dB, THD = –84dBc at 2MHz
LT®1568
Very Low Noise, High Frequency, Active RC,
Filter Building Block
LT1993-2/LT1993-4/
LT1993-10
800MHz/900MHz/700MHz Low Distortion, Low Noise
Differential Amplifier/ADC Driver
A = 2V/V / A = 4V/V / A = 10V/V, NF = 12.3dB/14.5dB/12.7dB,
V V V
OIP3 = 38dBm/40dBm/40dBm at 70MHz
LT1994
Low Noise, Low Distortion Fully differential Input/Output
Amplifier/Driver
Low Distortion, 2V , 1MHz: –94dBc, 13mA, Low Noise: 3nV/√Hz
P-P
LT6402-6/LT6402-12/ 300MHz Low Distortion, Low Noise Differential Amplifier/
A = 6dB/A = 12dB/A = 20dB, NF = 18.6dB/15dB/12.4dB,
V V V
LT6402-20
LTC6404-1
LTC6404-2
LTC6404-4
ADC Driver
OIP3 = 49dBm/43dBm/51dBm at 20MHz
Fully Differential Amplifier, GBW = 500MHz
Fully Differential Amplifier, GBW = 900MHz
Fully Differential Amplifier, GBW = 1700MHz
Very Low Distortion, (2V , 10MHz): –91dBc
P-P
Very Low Distortion, (2V , 10MHz): –96dBc
P-P
Very Low Distortion, (2V , 10MHz): –101dBc
P-P
LT6600-2.5/LT6600-5/ Very Low Noise, Fully Differential Amplifier and Filter
LT6600-10/LT6600-20
2.5MHz/5MHz/10MHz/20MHz Integrated Filter, 3V Supply,
SO-8 Package
LTC6602
Dual, Matched Bandpass Filter
Programmable Gain and Bandwidth for RFID Applications
(40kHz to 1MHz)
LTC6603
Dual, Matched Lowpass Filter
Dual, Matched Lowpass Filter
Dual, Matched Lowpass Filter
Programmable Gain and Bandwidth (25kHz to 2.5MHz)
2.5MHz, 5MHz, 10MHz and 15MHz
LTC6604-X
LTC6605-X
7MHz, 10MHz and 14MHz
66011f
LT 1108 • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
40
●
●
© LINEAR TECHNOLOGY CORPORATION 2008
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
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